JP4827346B2 - Rubber press molding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber press molding method for obtaining a shaped product by hydrostatic pressure.
[0002]
[Prior art]
Conventionally, a rubber press molding method has been widely used as a molding means for obtaining a green compact with an isotropic structure. In this molding method, after a rubber powder is filled with a fine powdery molding powder, the molding is performed by applying uniform hydrostatic pressure from all directions through a liquid medium.
[0003]
As such a rubber press molding method, for example, in Japanese Patent Publication No. 7-108477, a molded article of an arbitrary shape made of an organic material that can be plastically deformed and has a small amount of springback is used as a core in a rubber case. A rubber press molding method is disclosed in which a hydrostatic pressure is applied in a set state to obtain a crucible or a cylindrical generated shape.
[0004]
According to the rubber press molding method disclosed in the above publication, the molded product made of the organic material can relieve the spring back action of the rubber case that occurs in the pressure-lowering stage when the formed body is molded by hydrostatic pressure. Therefore, the formed shape to be molded is hardly subjected to large stress or interfacial friction force, and it is possible to prevent the above-mentioned generated shape from causing molding defects such as cracks and breakage, and to always achieve the desired generation with high molding efficiency. The shape could be molded.
[0005]
However, in the rubber press molding method disclosed in the above publication, since the molding powder that is the raw material of the generated shape and the molded product of an arbitrary shape made of an organic material are in direct contact with each other, In some cases, foreign substances such as impurities and organic material particles contained in the material are dropped and mixed into the molding powder, and it is impossible to form a high purity product.
[0006]
If the high-purity shaped product cannot be molded in this way, for example, when the molded powder is a carbonaceous material, it is mixed into the molded powder in the firing step and graphitization step performed after the molded shaped product is molded. By burning and removing foreign matters such as impurities and organic material particles, defects such as pinholes are generated in the carbon product to be manufactured, and it is difficult to manufacture a product without defects.
Further, in the rubber press molding method disclosed in the above publication, the molded product may move with respect to the rubber case during the rubber press, and it is difficult to obtain a generated shape having a desired shape.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and impurities and foreign substances are not mixed in the raw material molding powder during the molding process. It is an object of the present invention to provide a rubber press molding method capable of molding a rubber.
[0008]
[Means for Solving the Problems]
The rubber press molding method of the first aspect of the present invention is a rubber press molding method for producing a three-dimensional shaped shaped product by filling a rubber case with molding powder and applying hydrostatic pressure,
In a state where the resin molded product is set in the rubber case so that most of the resin molded product of a predetermined shape is in contact with the outside of the rubber case, the rubber powder is filled with the molded powder, The hydrostatic pressure is applied.
[0009]
The rubber press molding method according to the second aspect of the present invention includes a bottomed cylindrical shape in the concave portion of the rubber case in which a concave portion is formed in the vicinity of the center of the lower surface and has a space having a shape similar to a generated shape to be molded. After fitting the foamed resin molded product with the opening facing downward and filling the rubber case with the molding powder, the rubber case is placed in the liquid medium of the hydrostatic pressure device, Air inside the foamed resin molding is removed, the liquid medium is filled into the foamed resin molding, and hydrostatic pressure is applied to the molding powder.
Hereinafter, the present invention will be described in detail.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
First, the rubber press molding method of the first present invention will be described.
The rubber press molding method of the first aspect of the present invention is a rubber press molding method for producing a three-dimensional shaped shaped product by filling a rubber case with molding powder and applying hydrostatic pressure,
In a state where the resin molded product is set in the rubber case so that most of the resin molded product of a predetermined shape is in contact with the outside of the rubber case, the rubber powder is filled with the molded powder, The hydrostatic pressure is applied.
[0011]
Here, “the state where the resin molded product is set in the rubber case so that most of the resin molded product of a predetermined shape is in contact with the outer side of the rubber case” means that the rubber case that is bag-like and easily deformed is broken. Without embedding the resin molded product of a predetermined shape from the outside to the inside of the rubber case so that a part thereof is exposed, the space inside the rubber case was approximated to the shape of the generated shape to be molded A state that is deformed into a shape.
That is, according to the rubber press molding method of the first aspect of the present invention, it is possible to produce a formed body in which a recess having substantially the same shape as the outer shape of the resin molded product is formed on at least a part of the surface thereof.
[0012]
Hereinafter, the rubber press molding method of the first present invention will be described with reference to the drawings.
1 (a), 1 (b), 2 (a), and 2 (b) are explanatory views schematically showing how a three-dimensional shape generated shape is produced by the rubber press molding method of the first present invention. It is.
[0013]
In the rubber press molding method according to the first aspect of the present invention, first, as shown in FIGS. 1A and 1B, most of the resin molded product 12 having a predetermined shape is in contact with the outside of the rubber case 11. The resin molding 12 is set on the rubber case 11.
[0014]
The rubber case 11 is a container so that molding powder can be filled therein, and is made of a material that has a predetermined shape and can be easily deformed. Moreover, it may consist of a container and a lid, and may be configured so that the lid can be easily detached.
Such a material is not particularly limited, and examples thereof include synthetic rubbers such as styrene / butadiene rubber, isoprene rubber, chloroprene rubber, and acrylonitrile / butadiene copolymer rubber.
Further, the size is not particularly limited, and is appropriately determined according to the size of the generated shape to be molded.
[0015]
Further, as shown in the figure, the rubber case 11 may be deformed by embedding the resin molded product 12 in a form in which a part thereof is exposed. However, as described above, the rubber case 11 is formed into a predetermined shape. It is preferable that the resin molded product 12 is configured in advance so as to be embedded (fitted).
When the rubber case 11 is deformed by the resin molded product 12, it is possible to easily produce various shapes of generated shapes by changing the shape of the resin molded product 12, but the size of the obtained generated shapes is small. Easy to vary. On the other hand, when the rubber case 11 is formed in a predetermined shape in advance, it is possible to always produce a generated feature of a certain size, and there is almost no variation in size between the resulting generated features.
[0016]
The resin molded product 12 is not particularly limited, but is preferably a foamed resin molded product or a hollow rubber sphere. When the resin molding 12 is embedded from the outside of the rubber case 11, the rubber case 11 can be deformed without being damaged.
[0017]
When the resin molded product 12 is the above-mentioned foamed resin molded product, the shape thereof is not particularly limited, and is appropriately determined according to the shape of the generated shape to be molded. For example, the generated shape to be molded is a concave portion. In the case where the foamed resin molded product is, it is desirable that the foamed resin molded product is a cylindrical body.
[0018]
Furthermore, when the production | generation form used as shaping | molding object has a recessed part, it is desirable for the said foamed resin molding to be a bottomed cylinder shape. When producing a generated shape by hydrostatic pressure, all the surfaces including the inner wall portion of the recess formed in the generated shape because liquid enters the inside of the foamed resin molding and pressure acts from the inside. In addition, it is possible to apply a substantially uniform pressure and to impart a high degree of isotropy and a dense structure to the generated shape.
[0019]
Moreover, when the resin molding 12 is a hollow rubber sphere, it is desirable that the hollow rubber sphere can release the gas inside by pressurization. This is to prevent the hollow rubber ball from being damaged by the applied pressure when producing the generated shape by hydrostatic pressure.
[0020]
The raw material of the resin molded product 12 is not particularly limited. For example, when the resin molded product 12 is a hollow rubber ball, the same synthetic rubber as the rubber case 11 described above can be used. When 12 is a foamed resin molded product, for example, a foamed plastic can be used. Specific examples thereof include expanded polystyrene, expanded polyethylene, expanded polypropylene, and the like. Among these, expanded polystyrene is desirable. Although it is compressed and deformed, it is difficult to return to its original shape after being deformed, so that the spring back property is small and spray molding is possible, so that a desired shape can be easily produced. .
[0021]
Next, as shown in FIG. 2A, the molding powder 13 is filled in the space of the rubber case 11.
At this time, it is necessary to densely fill the molding powder 13 so that there is no gap between the rubber case 11 and the molding powder 13. If there is a gap between the rubber case 11 and the molding powder 13, the generated shape to be molded becomes an irregular shape, and it becomes difficult to produce a generated shape having a desired shape.
[0022]
Moreover, it does not specifically limit as such a molding powder 13, For example, a carbonaceous material, a ceramic material, etc. can be mentioned.
[0023]
The carbonaceous material is not particularly limited, and examples thereof include graphite powder, carbon black, coke powder, and tar pitch. These may be used alone or in combination with a plurality of materials.
The ceramic material is not particularly limited. For example, a nitride ceramic such as aluminum nitride, silicon nitride, boron nitride, or titanium nitride, a carbide ceramic such as silicon carbide or titanium carbide, or an oxide such as alumina, silica, or zirconia. A ceramic etc. can be mentioned.
[0024]
Here, when the molding powder 13 is a carbonaceous material composed of coke powder and tar pitch, the blending amount is preferably 10 to 80 parts by weight with respect to 100 parts by weight of coke.
The molding powder 13 is prepared by kneading the raw material powder with a kneader or the like to obtain a bulky raw material composition, and then pulverizing it with a pulverizer or the like to make the average particle size about 20 to 30 μm. Can do.
[0025]
Then, as shown in FIG. 2 (b), the rubber case 11 in which the molding powder 13 is sealed is placed in the liquid medium 16 of the hydrostatic pressure device 15, and the molding powder 13 is hydrostatically pressurized. Create a generated shape of the dimensional shape.
[0026]
The hydrostatic pressure device 15 is not particularly limited, and a hydrostatic pressure device usually used in rubber press molding can be used. Moreover, it does not specifically limit as the liquid medium 16, For example, water can be used.
[0027]
In addition, when the resin molded product 12 is formed into a bottomed cylindrical shape of a foamed resin molded product and a formed product having a recess is produced, air inside the foamed resin molded product is removed, and a fluid (liquid) is placed inside the foamed resin molded product. It is desirable to press the hydrostatic pressure of the molding powder 13 with the medium 16) filled.
The pressure applied to the outer periphery of the rubber case 11 and the pressure applied to the inside of the rubber case 11 can be made the same, and a generated shape having a high degree of isotropicity and a dense structure is produced. Because you can.
[0028]
The conditions for pressurization of the hydrostatic pressure are appropriately determined in consideration of the material and composition of the molding powder 13, the size of the generated shape, and the like, but generally it is preferably about 60 to 150 MPa. When the pressure is less than 60 MPa, the strength of the produced shaped product to be produced is insufficient and the shape stability is poor. On the other hand, when the pressure exceeds 150 MPa, the physical properties of the produced shape to be produced no longer improve, which is disadvantageous in terms of time and cost.
[0029]
As described above, according to the rubber press molding method of the first aspect of the present invention, since the resin molding and the molding powder are not in direct contact with each other, foreign matters such as impurities and foamed resin particles contained in the resin molding are contained in the molding powder. It is possible to produce a high-purity, defect-free three-dimensional shape generation product.
Therefore, a product such as a crucible or the like which is free from pinholes and has no defects in a carbon product or the like produced by firing the produced shape produced by the rubber press molding method of the first present invention. Can be reliably manufactured.
Moreover, since the resin molded product does not move relative to the rubber case during the rubber press, a generated shape having a desired shape can be reliably produced.
[0030]
Next, the rubber press molding method of the second present invention will be described.
The rubber press molding method of the second aspect of the present invention is a bottomed cylindrical foam formed in the concave portion of the rubber case having a concave portion formed in the vicinity of the center of the lower surface thereof and having a space having a shape approximate to the generated shape to be molded. The resin molded product is fitted so that the opening faces downward, and the rubber case is filled with molding powder, and then the rubber case is placed in a liquid medium of a hydrostatic pressure device, and the foam resin Air inside the molded product is removed, the liquid medium is filled into the foamed resin molded product, and hydrostatic pressure is applied to the molded powder.
[0031]
3 (a) and 3 (b) are explanatory views schematically showing how a generated shape is produced by the rubber press molding method of the second invention.
[0032]
As shown in FIG. 3A, in the rubber press molding method according to the second aspect of the present invention, first, a recess 34 is formed near the center of the lower surface thereof, and has a space having a shape approximate to the generated shape to be molded. A bottomed cylindrical foamed resin molding 32 is fitted into the recess 34 of the rubber case 31 with the opening 37 facing downward.
[0033]
The rubber case 31 has a recess 34 formed near the center of the lower surface thereof. By using the rubber case 31 having such a shape, it is possible to obtain a bottomed cylindrical shape.
Further, as described in the rubber press molding method of the first aspect of the present invention, since the rubber case 31 is formed in a predetermined shape in advance, it is possible to always produce a generated shape having a constant size.
In addition, about the material and magnitude | size of the rubber case 31, the thing similar to the rubber case 11 demonstrated by the rubber press molding method of said 1st this invention can be mentioned.
[0034]
The shape and size of the recess 34 are not particularly limited, and are appropriately determined according to the size of the generated shape to be molded.
In such a recess 34, a bottomed cylindrical foamed resin molded body 32 is fitted so that the opening 37 faces downward. This is because when the hydrostatic pressure is applied, the inside of the opening 37 is also filled with a liquid, and pressure is applied from the inside of the foamed resin molded product 32 to the rubber case 11 filled with the molding powder.
[0035]
The outer diameter and height of the bottomed cylindrical foamed resin molded article 32 are just large enough to fit into the recess 34, but the inner diameter is determined by the foamed resin molded article 32 when hydrostatic pressure is applied. The size is appropriately adjusted so as not to be deformed or broken. Specifically, the thickness of the foamed resin molded product 32 is preferably about 1 to 10% of the outer diameter of the rubber case 31. If it exceeds 10%, the foamed resin molded product 32 becomes too thick, and it becomes difficult to remove the foamed resin molded product 32 from the rubber case 31 after rubber press molding. On the other hand, if it is less than 1%, the strength of the foamed resin molded product 32 itself is lowered and may be easily damaged.
[0036]
Moreover, it does not specifically limit as a material of the foaming resin molding 32, The thing similar to the foaming resin molding which is an example of the resin molding 12 demonstrated by the rubber press molding method of said 1st this invention is mentioned. it can.
[0037]
Next, the molding powder 33 is filled into the rubber case 31.
When filling the molding powder 33 into the rubber case 31, it is necessary to fill the molding powder 33 closely so that there is no gap between the space of the rubber case 31 and the molding powder 33. . As described in the rubber press molding method of the first present invention. Moreover, the raw material which comprises the shaping | molding powder 33, and its preparation method can mention the raw material and preparation method similar to the shaping | molding powder 13 mentioned above.
[0038]
Next, as shown in FIG. 3B, the rubber case 31 filled with the molding powder 33 is placed in the liquid medium 36 of the hydrostatic pressure device 35. By arranging the rubber case 31 in the liquid medium 36 in this way, air remains in the foamed resin molded product 32, and when the foamed resin molded product 32 is arranged in the liquid medium 36 due to the buoyancy of the air. The foamed resin molded product 32 is not detached from the rubber case 31.
[0039]
Next, the air inside the foamed resin molded product 32 is removed, and the liquid medium 36 is filled into the foamed resin molded product 32. The inside of the foamed resin molded product 32 and the periphery of the rubber case 31 are set to the same pressure, so that a high degree of isotropy and a dense structure are imparted to the formed product to be produced. This is to prevent deformation or damage.
[0040]
The method for removing the air inside the foamed resin molded product 32 is not particularly limited, and examples thereof include a method of sucking out air with a pump such as a suction pump.
In addition, by removing the air inside the foamed resin molded product 32, the foamed resin molded product 32 cannot obtain the buoyancy of the air. However, since the rubber case 31 is already disposed in the liquid medium 36. The foamed resin molded product 32 is not detached from the rubber case 31 due to the pressure applied from the liquid medium 36.
[0041]
And the hydrostatic pressure pressurization of the molding powder 33 with which the inside of the rubber case 31 was filled is produced, and the production | generation form of a three-dimensional shape is produced.
The hydrostatic pressure of the molding powder 33 can be performed under the same conditions as described in the rubber press molding method of the first invention described above.
[0042]
As described above, according to the rubber press molding method of the second aspect of the present invention, the foamed resin molded product and the molding powder are not in direct contact with each other, so that impurities contained in the foamed resin molded product, foamed resin particles, etc. A foreign substance is not mixed in the molding powder, and a high-purity and defect-free three-dimensional shape generated shape can be produced.
Therefore, a product such as a crucible or the like that is free from pinholes and has no defects in a carbon product or the like produced by firing the formed shape formed by the rubber press molding method of the second invention. Can be reliably manufactured.
In addition, since the foamed resin molded product does not move with respect to the rubber case during the rubber press, it is possible to reliably produce a generated shape having a desired shape.
In the first and second rubber press methods of the present invention, no spring back action or the like occurs and no cracks or the like occur in the generated shape.
[0043]
【Example】
Hereinafter, the present invention will be described based on examples.
[0044]
Example 1
A recess having a diameter of 300 mm and a height of 700 mm was provided on the lower surface of a cylindrical rubber case (thickness 10 mm) having a diameter of 500 mm and a height of 1000 mm.
And the bottomed cylindrical foamed resin molding which consists of a polystyrene foam with an outer diameter of 300 mm, an inner diameter of 250 mm, and a height of 700 mm was fitted in the said recessed part so that the opening part might face the lower side.
[0045]
Next, the raw material composition obtained by mixing 50 parts by weight of tar pitch with 100 parts by weight of petroleum coke fine powder is kneaded with a kneader to form a lump, and then pulverized using a pulverizer to obtain an average particle diameter. The rubber molding powder finely pulverized to 25 μm is filled in the rubber case and hydrostatically pressurized at a pressure of 100 MPa by a hydrostatic pressure (CIP) device according to a conventional method, an outer diameter of 420 mm, an inner diameter of 250 mm, and a height of 820 mm. A bottomed cylindrical shape was produced.
No cracks, breakage, or the like was observed in the resulting generated shape, and a generated shape having a desired shape could be produced.
[0046]
Then, the produced shaped body is heated and fired at 1000 ° C. under a temperature rising condition of 1.5 ° C./hour in a reducing atmosphere, and then the obtained sintered body is 50 ° C. in a reducing atmosphere. The mixture was graphitized by heating to 3000 ° C. under a temperature rising condition of / hour to produce a crucible made of graphite.
[0047]
Comparative Example 1
Inside a cylindrical rubber case (thickness 10 mm) having a diameter of 500 mm and a height of 1000 mm, a cylindrical container made of foamed polystyrene having an outer diameter of 300 mm, an inner diameter of 250 mm, and a height of 700 mm at the center thereof has a particle size of 0.3. A molded product filled with ˜1.0 mm coke grains was set as a core.
[0048]
Next, after filling the space of the rubber case with the carbonaceous molding powder so as to cover the molded product with the same carbonaceous molding powder as in Example 1, hydrostatic pressure is applied under the same conditions as in Example 1. Produced features were made.
No cracks, breakage, etc. were observed in the resulting generated shape, but the molded product set in the rubber case as the core moved and the generated shape with the desired shape could be produced. There wasn't.
[0049]
Thereafter, firing and graphitization were performed under the same conditions as in Example 1 to produce a crucible made of graphite.
[0050]
Regarding the crucibles manufactured in Example 1 and Comparative Example 1, it was confirmed whether or not pinholes existed. As a result, no pinholes were confirmed in the crucible according to Example 1, and it was sintered very densely. However, the crucible according to Comparative Example 1 was confirmed to have a plurality of pinholes and had defects.
【The invention's effect】
As described above, according to the rubber press molding method of the first and second present invention, since impurities and foreign matters are not mixed in the raw material molding powder in the molding process, high purity and no defects, It is possible to reliably produce a target product having a desired shape, and a carbon product obtained thereafter does not have pinholes and the like, and a dense product free from defects can be produced.
[Brief description of the drawings]
FIGS. 1A and 1B are explanatory views schematically showing how a generated shape is molded by the rubber press molding method of the first invention.
FIGS. 2 (a) and 2 (b) are explanatory views schematically showing how a formed shape is molded by the rubber press molding method of the first present invention.
FIGS. 3A and 3B are explanatory views schematically showing how a generated shape is molded by the rubber press molding method of the second invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11, 31 Rubber case 12 Resin molding 13, 33 Molding powder 15, 35 Hydrostatic pressure presser 16, 36 Liquid medium 32 Foamed resin molding 34 Rubber case 37 Opening

Claims (1)

  A concave portion is formed near the center of the lower surface, and a bottomed cylindrical foamed resin molded product is opened downward in the concave portion of the rubber case having a space having a shape similar to the generated shape to be molded. The rubber case is placed in a liquid medium of a hydrostatic pressure device, and the air in the space formed by the inner wall of the foamed resin molded product is fitted into the rubber case and filled with molding powder. The rubber press molding method is characterized in that the liquid medium is filled in a space formed by the inner wall of the foamed resin molding, and the molding powder is hydrostatically pressurized.

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